Crankshaft driven reciprocating piston pump having plural guide rods

ABSTRACT

The pump is formed by a body having a cavity with a cylindrical chamber in which a piston is reciprocated toward and away from an inlet and outlet aperture. A crank shaft extends through an aperture formed through the piston transverse to its axis and through opposite walls of the cavity. The crank shaft has a cam located in the piston aperture. Upon rotation of the crank shaft, the cam alternately engages opposite facing cam surfaces of the piston in the piston aperture to reciprocate the piston to draw fluid into the chamber from an inlet path and then to pump the fluid out through an outlet path. The piston has spaced apart O-rings on its outer wall which engage the chamber wall upon reciprocation of the piston.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a pump for pumping fluid in an ammoniarefrigeration system.

2. Description of the Prior Art

An ammonia refrigeration system generally comprises a generator, acondenser, a chiller, an absorber and a pump for pumping fluid from theabsorber to the inlet of the generator.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a new and useful fluid pumpuseful in an ammonia refrigeration system.

The pump comprises a body having a cavity including a cylindricalchamber for supporting a piston for reciprocation between in first andsecond opposite directions in the chamber. First and second axiallylocated guide apertures extend into the walls of the pump body. Thepiston has first and second opposite ends with first and second axiallylocated guide rods which are located in the first and second guideapertures respectively. The first guide rod has an axial aperture and aradial aperture in fluid communication with each other. A one way inletvalve is located in the first aperture upstream of the first guide rodfor allowing fluid flow only into the chamber by way of the firstaperture. An outlet aperture extends through the wall of the bodytransverse to the axis of the chamber in fluid communication with thefirst aperture between the one way inlet valve and the chamber. A oneway outlet valve is located in the outlet aperture to allow fluid flowonly from the outlet aperture out of the pump. A crank shaft receivingaperture is formed through the piston transverse to its axis.Diametrically opposed crank shaft apertures are formed through the bodyin communication with the cavity of the body transverse to the axis ofthe chamber. A rotatable crank shaft extends through the crank shaftapertures of the body and through the crank shaft aperture of thepiston. The crank shaft has a cam located in the crank shaft receivingaperture of the piston for alternately engaging two cam surfaces axiallyspaced apart and facing each other in the crank shaft receiving apertureof the piston for reciprocating the piston upon rotation of the crankshaft. Upon movement of the piston in the second direction, the one wayinlet valve allows fluid to flow into the chamber by way of the axialand radial apertures of the first guide rod and upon movement of thepiston in the first direction, the piston causes fluid in the chamber tobe forced outward through the one way outlet valve by way of the radialand axial apertures.

In a further aspect two spaced apart O-ring seals are located at thefirst end of the piston for engaging the interior wall of the chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of the pump of the invention showing theinlet and outlet and an end of the crank shaft.

FIG. 2 is an isometric view of the pump of FIG. 1 showing the driveconnector for use for rotating the crank shaft.

FIG. 3 is a cross-sectional view of the pump showing the piston in thepiston chamber and the crank shaft.

FIG. 4 is a cross-sectional view of the piston of the pump.

FIG. 5 is a view of FIG. 4 as seen along lines 5--5 thereof.

FIG. 6 is a side view of the bottom lid of the piston.

FIG. 7 is a plan view of the inside of the top block of the pump showingthe cylindrical chamber for the piston.

FIG. 8 is a side view of the top block of the pump.

FIG. 9 is a side view of the base block of the pump.

FIG. 10 is a side view of the base block of the pump rotated 90 degreesfrom that of FIG. 7.

FIG. 11 is a plan view of the inside of the base block of the pump.

FIG. 12 is a side view of the crank shaft of the pump without anybearings etc. thereon.

FIG. 13 is a plan view of the inlet cap of the pump.

FIG. 14 is a side view of a one way valve used in the invention.

FIG. 15 is a view of FIG. 14 as seen along lines 15--15 thereof.

FIG. 16 is a top plan view of the base plate.

FIG. 17 is a block diagram of an ammonia refrigeration system.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to FIGS. 1-3, the pump of the invention is identified byreference numeral 21. It is comprised of a body 23 having four sides 25,27, 29, and 31, a top end 33 and a bottom end 35 secured to a base plate37. The body 23 is formed of a base metal block 43 and a top metal block41 secured together with bolts 45. Block 41 has the top end 33 and baseblock 43 has the bottom end 35. The sides 25 and 27 of the top block 41are stepped in that ledges 33B are provided such that the sides 27 and31 each are in the form of an inverted T with a top at 33A. Caps 51 and53 are secured to the top portion 33A and to the side 27 of block 41respectively by bolts 52 and 54 and support inlet and outlet fittings 61and 63 respectively. Fittings 61 and 63 are identical. Caps 51 and 53are identical. A crank shaft 71 extends through the body forreciprocating a piston 81 (FIG. 4) located in a chamber or cavity 91 ofthe body 41 for causing fluid to be drawn into the chamber 91 from theinlet fitting 61 and then forced out from the chamber through outletfitting 63.

As shown in FIG. 17, in an ammonia refrigeration system, the inletfitting 61 may be coupled to a conduit 301 extending from an absorber303, and the outlet fitting 63 may be coupled to a conduit 305 extendingto a generator 307 to pump fluid from the absorber 303 to the generator307. In the system shown, ammonia gas is applied from the generator 307to a condenser 309 by way of conduit 311; the output of condenser 309 isapplied to a chiller 313 by way of a conduit 315 and the output of thechiller 313 is applied to the absorber 303 by way of conduit 317.Conduit 319 extends from the generator 307 to apply water back to theabsorber 303. The pump takes the combined ammonia-water solution fromthe absorber and pumps it into the generator against the pressure head.

Referring again to the pump 21, the top block 41 (FIG. 3) has acylindrical chamber 91 with at top wall 103 and a cylindrical side wall105 (FIG. 7) which extends to a rectangular chamber by way of a shoulder108. The chamber 107 has four side walls 109, 110, 111, and 112. The topwall has a cylindrical guide rod aperture 115 formed therein which leadsto a smaller diameter cylindrical aperture 117 which in turn leads to anupper cylindrical aperture 119 which receives a one way valve 121 whichallows fluid flow only in the direction of the arrow 123. The fitting 61allows fluid flow to the valve 121 by way of opening 125.

A cylindrical aperture 127 is in fluid communication with a apertures115 and 117. Aperture 127 leads to cylindrical aperture 129 in which aone way outlet valve 131 is located. Valve 131 allows fluid flow only inthe direction of the arrow 133. The fitting 63 allows fluid flow fromthe valve 131 by way of opening 135. Valves 121 and 131 are press fittedinto valve bodies 121B and 131B which are slip fitted into the apertures119 and 129.

The bottom of the block 41 has a flat surface 137. Four threaded boltholes 139 extend from ledge 33B to the surface 137. Two semicirculargrooves 141 and 143 are formed in the flat wall 137 from sides 25 and 29leading to the chamber 107. Two threaded bolt holes 145 extend fromledge 33B to the upper ends of the grooves 141 and 143.

The top of the block 43 has a flat surface 151 with a rectangularchamber 153 extending downward to a bottom surface 155. The chamber 153has four side walls 159, 160, 161, 162. The bottom wall 155 has acentral guide rod receiving aperture 165 extending therethrough. Inaddition, four threaded bolt holes 291 extend through the bottom wall156 for receiving bolts (not shown) for bolting the base block 43 to thebase member 37. Two semicircular grooves 171 and 173 are formed in thesurface 151 from sides 25 and 29 to the chamber 153.

The two blocks 41 and 43 are bolted together for forming a cavity 174including the piston chamber 91 and for forming two crank shaftapertures formed by grooves 141, 171 and 143, 173.

Four threaded apertures 163 extend through the block 43 for use inbolting the two blocks together. The piston 81 and the crank shaft 71are located in the chamber 91 and the cavity 174 with end of the crankshaft 71 located in the apertures 141, 171 and 143, 173.

Referring to FIGS. 3, 4, and 5, the piston 81 comprises a circularsurface 201 having an upper surface 203 and two spaced apart annulargrooves 205 and 207 for receiving two elastomer O-rings 209 and 211respectively. A central guide rod 213 extends from the surface 203. Anaxial aperture 215 is formed in the rod 213 from its end 213E to theplane of the surface 203. Two radial apertures 217 extend into the rod213 at the surface 203 from opposite sides intercepting the aperture215. An annular shaped linear bearing 216 (See FIG. 3) is press fittedin the aperture 119 within which the rod 213 can slide uponreciprocation of the piston 81.

A hollow cylindrical wall 221 extends from the back side of the wall 201having two diametrically opposed annular slots 223A and 223B formeddefining two arcuate wall sections 221A and 221B. The bottom side of thewall 201 has to a circular surface 225. The outer edge of the wall 201has a circular ridge 227 having the same diameter as that of circularridges 201A and 201B defining the two annular slots 205 and 207. Theoutside diameter of the wall sections 221A and 221B is less than that ofthe ridge 227 with a shoulder 229 therebetween. The ends 235 of the wallsections 221A and 201B are flat. Four threaded apertures 237 are formedin the flat surfaces 237 of the wall sections 221A and 221B.

A circular bottom lid 241 (FIG. 6) is provided having a front side 243and a bottom side 245. Bolt holes 247 are formed through the lid 241 foralignment with the apemares 237. The lid 241 is attached to the fiatsurfaces 235 of the wall sections 221A and 221B with bolts 249 whichextend through apertures 247 and are screwed into apertures 237 as shownin FIG. 3. This forms a crank shaft aperture 223A, 223B extendingthrough the piston 81 transverse to its axis 81A.

The bottom side of the lid 241 has a cylindrical guide rod 251 extendingtherefrom. The rod 251 has a smaller diameter rod 251A extendingtherefrom with an annular snap ting holding slot 253 formed therein. Ahardened sleeve 255 (See FIG. 3) is press fitted around the rod 251. Alinear ring shaped bearing 257 is located in the aperture 165 of thebottom wall 155 of base block 43 within which the rod 251 slides uponreciprocation of the piston 81. The bearing 257 is held in place by snaprings 258.

Referring to FIGS. 3 and 12 the crank shaft 71 comprises a cylindricaldrive end 261, two cylindrical bearing portions 263 and 265, acylindrical cam portion 267 and a cylindrical stop portion 269. The axis267A of cam portion 267 is offset from the axis 71A of the rest of theshaft a small amount which in the preferred embodiments is 3/32 of aninch. Annular thrust bearings 271 and 273 are located around the camportion 267 on opposite sides of an annular bearing 275 around which islocated an annular roller 277. Cam portion 267, beating 275 and roller277 form a cam for reciprocating the piston. Member 281 is an annularspacer; member 283 is an annular thrust bearing; and member 285 is anannular beating press fitted around shah end 265. Member 287 is anannular thrust bearing and member 289 is an annular beating press fittedaround shaft position 263.

In assembling the pump, the shaft 71 with the beatings, spacer androller is located in the openings 223A, 223B of the piston 81 and thebottom lid 241 is secured to the bottom wall 235 of the cylindricalportions 221A and 221B. The guide rod 213 is inserted into the upperbearing 216 and the guide rod 251 is inserted into the lower bearing 257of the blocks 41 and 43 respectively. The block walls 137 and 151 aremoved together with the bearings 285 and 289 located in the shaftapertures 143, 173 and 141, 171 respectively. Bolts 45 are insertedthrough apertures 139 and screwed into apertures 163 to secure the twoblocks 41 and 43 together with the piston 81 and shaft 71 located in thechamber 91 and cavity 174 and the shaft ends located in the shaftapertures 141, 171 and 143, 173. Set screws 293 are screwed intoapertures 145 until they engage the bearings 285 and 289 to hold thebearings stationary relative to the block 41. Upon assembly of the pump,holes 170 formed through block 43 are aligned with the lid bolts 249.Final adjustment of the lid 241 to the piston 81 is made by insertingAllen head wrenches through holes 170 of the block to engage and adjustthe lid bolts 249. The one way valves 121 and 131 are press fitted intothe valve bodies 121B and 131B and the valve bodies are slip fit intothe apertures 119 and 129 respectively. The valves 121 and 131 areidentical as are the valve bodies. In FIG. 14 valve 121 and valve body121B are shown. As shown in FIGS. 14 and 15, each valve body has O-rings132 located in annular grooves formed in its opposite wall edges. Theinward facing O-rings 132 of the valve bodies 121B and 131B will seatagainst shoulders 119S and 129S of apertures 119 and 129. The block 43can be attached to the base 37 by screwing bolts (not shown) throughplate apertures 169 into threaded apertures 291 formed in the base 37.

The two fitting caps 51 and 53 are identical. As seen in FIGS. 8 and 13the caps 51 has four outer apertures 293 and a central threadedapertures 295. The fittings 61 and 63 are identical. They are screwedinto central apertures 295 of the caps 51 and 53. The caps 51 and 53 arelocated in place on surfaces 33A and 27 with the apertures 125 and 135aligned with apertures 119 and 129 respectively and attached to theblock 41 with bolts 52 and 54 which are screwed into threaded apertures298 and 299 formed in surfaces 33A and 27. The caps 51 and 53 bearagainst the valve outer O-rings 132 of the valve bodies 121B and 131B.

As shown in FIG. 2, a drive connector 300 is connected to the drivemember 261 of the shaft 71 to allow rotation of the shaft by a motor.Upon rotation of the shaft 71, the roller 275 of the cam alternatelyengages cam surfaces 225 and 243 of the piston 81, causing the piston toreciprocate in the chamber 91. In FIG. 3, the piston is shown in itsupper most position. In this position cam roller 277 engages the pistonsurface 225 but is spaced from the piston surface 243 about 0.003-0.005of an inch. The piston stroke is about 3/16 of an inch. As the cam shaft71 rotates 90 degrees and the cam roller 275 engages the piston surface243 to move the piston downward, a suction is drawn in the inletincluding aperture 117, which causes fluid to flow from inlet 61,through the one way inlet valve 121 into the chamber formed betweenpiston surface 203 and the upper chamber wall 103. Flow into the chamberis by way of axial aperture 215 and radial apertures 217 of the guiderod 213. As the piston moves downward, the radial apertures 217 aremoved into the chamber 91 between surfaces 203 and 103.

As the shaft 71 continues to rotate another 90 degrees causing the camroller 277 to engage the piston surface 255 and move the piston upward,fluid in the chamber between surfaces 203 and 103 is forced outward byway of radial apertures 217 and axial apertures 215 into apertures 117and transverse connecting apertures 127, through the valve 131 andoutlet fitting 63.

The cylindrical chamber 91 of the pump in which the top wall 201 of thepiston including ridges 201A, 201B and O-rings 209 and 211 and surface227 reciprocate in extends from the upper chamber wall 103 to the bottomedge 91B as seen in FIG. 8. Thus the piston stroke is short, 3/16 of aninch in the preferred embodiment. The top O-ring 209 seals the piston tothe cylindrical wall 91. The piston operates in a fluid solution with ahigh concentration of ammonia. It gets lubrication from the bottomO-ring 211 which captures grease between the two O-rings. As the bottomO-ring 211 advances in the cylinder 91, the bottom O-ring 211 appliesgrease on the cylinder wall. The blocks 41, 43, piston 81, pistonextension 241 and the crank shaft 71 are formed of a suitable metal.

In one embodiment, the components of the pump have the followingdimensions. These dimensions are in inches. It is to be understood thatthe components of the pump could have other dimensions.

D1=1.320

D2=2.25

D3=3.00

D4=1.700

D5=1.880-1.885

D6=1.941

D7=1.57

D8=0.093

D9=0.229

D10=0.093

D11=0.127

D12=0.873-0.874

D13=3.020

D14=3.365-3.367

D15=3.00

D16=1.94

D17=3.75

D18=4.00

D19=3.875

D20=5.875

D21=3.875-3.878

D22=5.875

D23=3.75

D24=4.00

D25=1.010

D26=6.879

D27=3.471-3.474

D28=1.204

D29=1.033

D30=1.204

D31=0.7495-0.7998

D32=0.9987-0.9997

D33=0.093

D34=1.25

We claim:
 1. A pump for pumping a fluid, comprising:a body having asurrounding wall forming a cavity with a cylindrical chamber withopposite first and second ends and with an axis extending between saidfirst and second ends, a piston located in said chamber for movement infirst and second opposite directions between said first and secondopposite ends respectively of said chamber, said piston having first andsecond opposite ends with an axis extending therebetween such that saidfirst and second ends of said piston move toward and away from saidfirst and second ends of said chamber respectively upon movement of saidpiston in said first direction and away from and toward said first andsecond ends of said chamber respectively upon movement of said piston insaid second direction, first and second apertures extending in said bodyfrom said first and second ends of said chamber respectively along theaxis of said chamber, first and second guide rods extending from saidfirst and second ends of said piston respectively along the axis of saidpiston, said first and second guide rods being movable in said first andsecond apertures respectively upon movement of said piston is said firstand second directions, inlet and outlet apertures formed in said body influid communication with said first aperture, an inlet one way valvelocated in said inlet aperture for allowing fluid to flow only from theexterior of said pump into said first aperture, an outlet one way valvelocated in said outlet aperture for allowing fluid to flow only fromsaid first aperture to the exterior of said body, an axial apertureformed in said first guide rod along the axis of said piston, at leastone radial aperture formed in said first guide rod transverse to theaxis of said piston and in fluid communication with said axial aperture,a crank shaft receiving aperture formed through said piston transverseto the axis of said piston, first and second diametrically oppositecrank shaft apertures extending through said wall of said body of saidcavity transverse to said axis of said chamber, a crank shaft extendingthrough said crank shaft apertures of said body and through said crankshaft receiving aperture of said piston and supported for rotation, saidpiston having first and second cam surfaces axially spaced from eachother and facing each other in said crank shaft receiving aperture, saidcrank shaft having a cam located in said crank shaft receiving apertureof said piston such that upon rotation of said crank shaft, said camalternately engages said first and second cam surfaces of said piston tomove said piston in said first and second directions respectively, uponmovement of said piston in said second direction, said inlet one wayvalve allows fluid to flow into said chamber by way of said axial andradial apertures of said first guide rod, upon movement of said pistonis said first direction, said piston causes fluid in said chamber to beforced outward through said outlet one way valve by way of said radialand axial apertures of said first guide rod.
 2. A pump for pumping afluid, comprising:a body having a surrounding wall forming a cavity acylindrical chamber with opposite first and second ends and with an axisextending between said first and second ends, a piston located in saidchamber for movement in first and second opposite directions betweensaid first and second opposite ends respectively of said chamber, saidpiston having first and second opposite ends with an axis extendingtherebetween such that said first and second ends of said piston movetoward and away from said first and second ends of said chamberrespectively upon movement of said piston in said first direction andaway from and toward said first and second ends of said chamberrespectively upon movement of said piston in said second direction,first and second apertures extending in said body from said first andsecond ends of said chamber respectively along the axis of said chamber,first and second guide rods extending from said first and second ends ofsaid piston respectively along the axis of said piston, said first andsecond guide rods being movable in said first and second aperturesrespectively upon movement of said piston is said first and seconddirections, inlet and outlet apertures formed in said body in fluidcommunication with said first aperture, said inlet and outlet aperturesbeing located transversely with respect to each other, an inlet one wayvalve located in said inlet aperture for allowing fluid to flow onlyfrom the exterior of said pump into said first aperture, an outlet oneway valve located in said outlet aperture for allowing fluid to flowonly from said first aperture to the exterior of said body, an axialaperture formed in said first guide rod along the axis of said piston,at least one radial aperture formed in said first guide rod transverseto the axis of said piston and in fluid communication with said axialaperture, a crank shaft receiving aperture formed through said pistontransverse to the axis of said piston, first and second diametricallyopposite crank shaft apertures extending through said wall of said bodyof said cavity transverse to said axis of said chamber, a crank shaftextending through said crank shaft apertures of said body and throughsaid crank shaft receiving aperture of said piston and supported forrotation, said piston having first and second cam surfaces axiallyspaced from each other and facing each other in said crank shaftreceiving aperture, said crank shaft having a cam located in said crankshaft receiving aperture of said piston such that upon rotation of saidcrank shaft, said cam alternately engages said first and second camsurfaces of said piston to move said piston in said first and seconddirections respectively, upon movement of said piston in said seconddirection, said inlet one way valve allows fluid to flow into saidchamber by way of said axial and radial apertures of said first guiderod, upon movement of said piston is said first direction, said pistoncauses fluid in said chamber to be forced outward through said outletone way valve by way of said radial and axial apertures of said firstguide rod.
 3. The pump of claim 2, comprising:first and second spacedapart O-ring seals located at said first end of said piston for engagingthe wall of said chamber.